一种圆锥形横电磁波传输室的分析

给出一种新型横电磁波传输室－圆锥菜横电磁波传输室,并在球坐标系下采用时域有限差分（FDTD）法对其场分布进行计算,分析了高阶模的影响,确定了传输室的上限工作频率范围。分析和计算结果表明,圆锥形横电磁波传输室的电场极化方向可任意改变,上限工作频率可达4GHz,具有广泛的应用前景。     

一种圆锥形横电磁波传输室的分析

给出一种新型横电磁波传输室－圆锥形横电磁波传输室,并在球坐标系下采用时域有限差分(FDTD)法对其场分布进行计算,分析了高阶模的影响,确定了传输室的上限工作频率范围。分析和计算结果表明,圆锥形横电磁波传输室的电场极化方向可任意改变,上限工作频率可达4GHz,具有广泛的应用前景。     

横电磁波传输室的三维FDTD法分析

本文运用时域有限差分（FDTD）法模拟电磁波在TEMcell（横电磁波传输室）中的传输，并对之进行了三维分析，给出了TEMcell中TEM模场的横截面分布及纵向分布；计算了TEM模与高阶模的谐振频率；分析了TEMcell的上限可用频率。此结果对横电波传输室的设计和使用具有重要意义。     

吉赫横电磁波传输室传输特性的宽频带分析

吉赫横电磁波传输室(GTEMcell)上限工作频率可达几个吉赫,因而在电磁兼容测量中得到越来越广泛的重视和应用。本文在非正交坐标系下采用FDTD(时域有限差分)法求解电磁波在GTEMcell中的传输特性,给出了GTEMcell中TEM模的横向分布和纵向分布,分析了高阶模对场分布均匀性的影响,由此确定了GTEMcell的上限工作频率范围。计算及分析结果对GTEMcell的设计和使用具有重要意义。     

EUT对TEM传输室基本特性影响的边界元分析

采用边界元法分析了不同尺寸的良导体受试设备(Equipment Under Test，EUT)对TEM传输室特性阻抗和场分布的影响，并估算了敏感度测试中EUT所承受暴露场强的大小。计算结果表明：与空载时相比当EUT满足“1／3准则”时，TEM传输室的特性阻抗下降值小于2Ω，EUT上、下方场强增加3～4dB，EUT上部所承受暴露场强比通常的估算方法高约4～6dB。测量结果与计算结果基本一致。     

微型计算机的电磁泄漏测量新技术

运行中的微型计算机要产生电磁泄漏，通常这种泄漏可认为是电气小的，且可用三个正交的电偶极矩和三个正交的磁偶极矩来描述，将一台微机作为受试设备放置在横电磁波小室的中心，它的泄漏能量耦合为基本的传输模，朝向小室的两个输出端口传播。通过测量可确定等效电偶极矩和等效磁偶极矩，进而计算出受试微机的泄漏功率，给出测量的基本原理和测试框图，并对测试结果进行讨论。     

大型吉赫横电磁波室的数值分析

为了解10m以上的大型GTEM（吉赫横电磁波）室的传输特性和场的均匀性,利用FDTD（时域有限差分）法对大型GTEM室进行了数值分析。选用了上升前沿为纳秒级的高空电磁脉冲波形和高频特性较好的高斯脉冲源作为激励源,计算结果表明对于10m长的GTEM室可以无失真地传输1．5GHz的电磁波,所以能够利用GTEM室传输上升前沿为纳秒级的快上升沿电磁脉冲。“三分之一”测试区域的场强不均匀性小于±2dB,可以用做精度较高的测量区域。     

吉赫横电磁波传输室传输特性的宽频带分析

吉赫横电磁波传输室（ＧＴＥＭ ｃｅｌｌ）上限工作频率可达几个吉赫,因而在电磁兼容测量中得到越来越广泛的重视和应用。本文在非正效坐标系下采用ＦＤＴＤ（时域有限差分）法求解电磁波在ＧＴＥＭ ｃｅｌｌ中的传输特性,给出了ＧＴＥＭ ｃｅｌｌ中ＴＥＭ模的模向分布和纵向分布,分析了高阶模对场分布均匀性的影响,由此确定了ＧＴＥＭ ｃｅｌｌ的上限工作频率范围。计算及分析结果对ＧＴＥＭ ｃｅｌｌ的设计和使用具有重要     

三导体TEM cell的场分布研究

本文采用时域有限差分（FDTD）法模拟了电磁波在三导体模电磁波室（T－TEM cell）中的传播,给出了T－TEM室在不同芯板加载情况下的横向场分布和纵向均匀性,并对其三维场分布进行了实际测量;将理论计算值与实测值进行比较后证实,芯板接地状况对场分布具有较大的影响,所得结果对T－TEM室的工程设计具有重要的指导意义。     

非对称横电磁波传输室的工程设计

本文利用非对称横电磁波传输室(ATEM Cell)的特性分析公式,给出了一套ATEMCell的工程设计方法。该方法借助计算机,实现了对ATEM Cell的三大参数(特性阻抗、截止频率和横向场分布)的优化设计。该方法的特点是,计算准确度高,方便工程应用。文中提供的数据图表为工程人员提供了更便捷的设计途径。     

加载横电磁传输室中的电场分布计算

用“准静脉法”研究了当工作频率远低于截止频率时,放置于横电磁传输室中的被测物体中的电场分布。文中使用的是有限差分法,给出了在三维空间中不同介质交界面上拉普拉斯方程的差分格式。计算结果表明当把ＥＴＵ放入ＴＥＭＣｅｌｌ的中心时,ＥＵＴ横截面上的电场分布是均匀的。     

A Comparison of the Currents Induced on an EUT in a TEM Cell to Those Induced in a Free-Space Environment

The finite-difference time-domain method is used to investigate whether the currents induced on equipment under test (EUT) in a transverse electromagnetic (TEM) cell are similar to those induced in a free-space environment. The approach is to simulate an identical EUT in both environments and determine a correlation based on the respective current distributions. The effect of the ratio of EUT to TEM cell sizes on the correlation to free space is also investigated. This paper introduces a metric that quantifies the change in the surface current induced on the EUT in these different environments.     

On the Interplay Between the Equipment Under Test and TEM Cells

In all applications of the gigahertz transverse electromagnetic (GTEM) cell, there is an interplay between the equipment under test (EUT) and the cell reflecting metal walls, as represented by images of the EUT. Moreover, owing to the multiple reflections within the cell and to its tapering structure, the phenomenon of illumination and reillumination of the EUT can hardly be avoided. These problems, known as reactive effects of the cell, are investigated in this paper. A simple new approach for an efficient investigation of the interactions between the EUT and the cell is provided. Closed-form expressions for the reflection coefficient, the relative deviation in field, and the relative error in the induced current caused by the reactive effect of the cell are derived. Each of these expressions encompasses both the mutual influence of the EUT's radar cross section (RCS) and the reactive effects of the cell. It is shown that depending on the frequency-dependent phase factor e^jpsi, strong and weak test conditions may occur since the overall incident field will exhibit maxima and minima. Hence, evidence showing that the total incident field impinging on the EUT generally deviates from the primary excited TEM field is provided. Moreover, the relative deviation in the field and the relative error in the induced current are quantified. Finally, the frequency dependence of the well-known one-third-rule of thumb is demonstrated.     

Impedance of TEM cells with equipment under test

A quasi-Tem approach based on conformal transformation is used to determine the characteristic impedance of a TEM cell with symmetric equipment under test (EUT), for efficient operation of the TEM cell. Some numerical results are presented.<>     

定向辐射式核电磁脉冲场模拟器的研制

针对大型受试设备核电磁脉冲抗扰度试验评估要求，研制了基于Marx发生器脉冲源和横电磁波（Transverse Electro Magnetic，TEM）喇叭天线的可移动、极化方向可调的定向辐射式核电磁脉冲模拟器.实验分析了不同极化方向和终端负载对脉冲波形的影响，确定了定向辐射式核电磁脉冲模拟器的均匀区域.结果表明:辐射电磁脉冲场可用区域为近场区域，随着与口径面距离的增大，峰值场强近似按1/d2衰减，脉冲宽度显著减小；与传输式模拟器相比，辐射式核电磁脉冲模拟器具有更大的均匀区域，更适合大型设备电磁脉冲抗扰度试验.     

混响室条件下线缆共模干扰临界辐射干扰场强测试研究

为在混响室中线缆共模干扰时的设备(EUT)进行临界辐射干扰场强测试,并确保与开阔场中测试结果一致,该文推导了线缆上共模电流满足的方程,将共模电流分解为相应的特征电流,计算了终端负载任意时线缆最大方向性系数的变化范围。以单导体传输线和同轴线为EUT,分别在混响室和开阔场中测试线缆的临界干扰场强,对计算结果进行了验证。结果表明:最大方向性系数的计算结果可以保证两种不同场地中测试结果的一致性,双线的共模干扰以及同轴线均可以等效为单线,且线缆弯曲对测试结果基本没有影响。     

Investigation of radiated susceptibility during EFT tests

The aim of this paper is to focus on a problem: during an electrical fast transient (EFT) conducted susceptibility test, a very strong radiated field is produced and a radiated coupling with the internal circuitry of the equipment under test (EUT) occurs. Therefore in case of EUT malfunctions, it is difficult to understand whether the resulting failures are due to the injected conducted current (requiring a filtering action) or to the impinging radiated EM field (requiring a shielding action). A model to describe the EM radiation, coming from the current flowing along the EUT power cord, is presented as well as its experimental validation     

A treatment of the phase properties of GTEM to open-area test-sitecorrelation techniques

The gigahertz transverse electromagnetic (GTEM) cell is a very attractive environment for the measurement of radiated emissions from electrically small equipment under test (EUTs). However, the GTEM is only accepted by the relevant measurement standards as long as the measurements in a GTEM can be used to predict the field that a particular EUT would produce on an open-area test site (OATS). Techniques for predicting equivalent OATS radiated fields from measurements in a GTEM have been developed. The techniques include the assumption that the dipole moments, which represent the radiation of an EUT, are all in phase. We analyze the case where the EUT dipole moments are not in phase and propose a new upper limit for the predicted OATS radiated field. Our new limit is up to 5 dB greater than the maximum predicted by the existing techniques, but over most of the frequency range the difference with the existing technique is about 3 dB     

近场辐射电磁干扰模态测试系统设计

提出近场辐射电磁干扰模态测试方法,设计近场模态检验测试系统,采用近场电磁场头对待测设备进行扫描式测量,获得待测设备的近场电磁场分布情况,并根据测得电磁场强度大小可分析得到待测设备的辐射EMI模态。实验结果表明,该方法可对电子电路的近场辐射EMI模态进行有效识别和检验,分别得到近场辐射共模噪声和差模噪声EMI模态,为辐射电磁干扰噪声的抑制提供有益参考。